8/13/2019 SKF Sealing http://slidepdf.com/reader/full/skf-sealing 1/60 Industrial seals Product overview
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 1/60
Industrial sealsProduct overview
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 2/60
2
Contents
SKF – the knowledge engineering company 3
SKF industrial seals and accessories overview 4
Radial shaft seals 5
Sealing lip material overview 6
Small diameter seals 7
Seals with nitrile or fluoro rubber sealing lips 8
Seals with PTFE sealing lips 11
Large diameter seals 12
Metal-cased seals 13
Fabric-reinforced seals 17
Metal-inserted seals 18
All-rubber seals 19
Permissible operating conditions 20
Cassette seals and shaft sealing units 22 SKF Mudblock cassette seals 23
SKF SCOTSEAL sealing units 24
Wear sleeves 25
Axial shaft seals 26
V-ring seals 27
Metal-cased V-type sealing rings and axial clamp seals 29
Mechanical seals 30
Hydraulic seals 31
Material overview 32
Piston seals 33
Selection matrix 40
Rod seals 41 Selection matrix 48
Wiper seals 49
Selection matrix 53
Guides 54
Static seals 55
O-rings 56
Back-up rings 57
Product index 58
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 3/60
3
SKF – the knowledgeengineering company
The SKF Group is the leading global supplier of products, solutions and services in
the field of rolling bearings, seals, mechatronics, services and lubrication. The servicesoffered by the SKF group include technical support, maintenance services, condition
monitoring and training.
SKF was founded in 1907 and grew at a rapid rate to become a global company.
As early as 1920, the company was well established in Europe, America, Australia,
Asia and Africa. Today, SKF is represented in more than 130 countries. The company
has more than 100 manufacturing sites and sales companies supported by some
15 000 distributors. SKF also has a widely used e-business marketplace and an
efficient global distribution system.
The SKF Group has a global 14001 environmental certification and a global OHAS
18001 health and safety management certification. Individual divisions have been
approved for quality certification in accordance with ISO 9001. The automotivebusiness units are also certified according to ISO/TS 16949:2002.
From the company that invented the self-aligning ball bearing 100 years ago, SKF has
evolved into a knowledge engineering company that uses its experience and technical
expertise to create unique value propositions for its customers. These solutions are
based on our technical knowledge and capabilities within five closely related technology
platforms, namely bearings and units, seals, mechatronics, services and lubrication
systems.
Complemented by a worldwide service network and manufacturing footprint, SKF
value propositions are available wherever and whenever customers need them.
SKF stands ready to serve the market with world-class products, competencies,
intellectual resources and a vision for success.
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 4/60
SKF industrial seals andaccessories overviewThe SKF range of industrial seals and accessories is divided into five main groups; radial shaft seals, wear sleeves, axial shaft
seals, hydraulic seals and static seals. The purpose of this publication is to provide an overview of the main products within
these groups, their characteristics and suitability for different application conditions. Detailed information about the products
can be found in the SKF catalogues “Industrial shaft seals” and “Hydraulic seals”.
Radial shaft seals Hydraulic seals Static seals
Small diameterradial shaft seals
Piston seals O-rings
Large diameterradial shaft seals
Wear sleeves
SKF SPEEDI-SLEEVE
Large diameterwear sleeves
Rod seals Back-up rings
Cassette sealsand sealing units
Axial shaft seals
V-ring seals
Metal-cased V-ringseals & axial clamp seals
Mechanical seals Wiper seals
Guides
4
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 5/60
Radial shaft sealsWhenever a shaft rotates, it needs a bearing arrangement for smooth and effective operation.
Wherever there is a bearing, there is also a need for an appropriate sealing solution to protect
that bearing, so that it operates reliably and achieves maximum service life. The performance and
service life of a bearing arrangement is directly related to the sealing solution’s ability to fulfil its
four main tasks:
The most common types of seals used to protect bearing arrangements in general industrial
applications are radial shaft seals for shaft diameters up to 203 mm (8 in). Large diameter seals,
for shaft diameters above 203 mm, have special features and are intended for use in large-size
and heavy-duty applications.
On the following pages, the standard range of SKF radial shaft seals is presented with a short
description. In depth technical product information can be found in the catalogue “Industrial shaft
seals”. For information about availability and delivery time, please contact your nearest SKF
representative or authorized distributor.
a. Radial shaft seal
b. Lubricant
c. Shaft
d. Bearing
4. Exclude dirtand moisture
3. Seal underpressure
2. Separate twodifferent media
1. Retainthe lubricant
ab
c
d
5
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 6/60
6
Shaft seals
Sealing lip material overviewIn addition to seal design, the sealing lip material significantly contributes to seal performance and
reliability. In order to accommodate different application requirements, SKF seals are produced in a
variety of sealing lip materials, see table below. These materials have characteristics and individual
properties that make them particularly suitable for specific applications.
Details about the physical properties and chemical resistance of seal materials to various media
encountered in operation can be found in the section “Chemical resistance” in the catalogue
“Industrial shaft seals”.
Codes are used to identify the sealing lip material of SKF seals. The codes for the most commonlyused seal materials are listed in the table below. The codes also appear in the designations of
radial shaft seals. For seals produced from a combination of materials, a combination of the code
letters is used, e.g. RV (nitrile rubber and fluoro rubber).
SKF seals are available in several other materials on request. Please contact your SKF sales
representative or authorized distributor for more information.
SKF sealing lip materials
Composition of basic material Designation according to
SKF ISO 1629/ ASTM1) D1418
Acrylonitrile-butadiene rubber (nitrile rubber) R, RG NBR
Hydrogenated acrylonitrile-butadiene rubber(SKF DURATEMP)
H HNBR
Carboxylic-acrylonitrile-butadiene rubber (Duralip) D XNBR
Fluoro rubber (LongLife) V FKM
Polytetrafluoroethylene T PTFE
1) American Society for Testing and Materials
IMPORTANT SAFETY NOTE: At temperatures above +300 °C (+570 °F), all fluoro elastomersand PTFE compounds give off dangerous fumes. If there is unintentional contact with yourskin or if the vapours have been inhaled, a doctor should always be consulted.
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 7/60
Radial shaft seals
Small diameter sealsSKF small diameter radial shaft seals are the most common seals and are used for shaft diameters
ranging from 3 to 203 mm (0.125 to 8 in). These seals are available in a wide range of designs
and materials to meet the varying demands of different applications. See Matrix 1 for an overview.
This chapter presents the most commonly used small diameter radial shaft seals within the SKF
range. Most of these seals conform to one of the designs standardized in the international or
national standards, for example ISO, ASTM, DIN or JIS.
Radial shaft seals overview Matrix 1Small diameter range
Design
Outside diameter Sealing lip Auxiliarylip
R, RG Nitrile rubberV Fluoro rubberPTFE Polytetrafluoroethylene
Seal types C o n f i g u r a t i o n
M a t e r i a l c o d e
C o n f i g u r a t i o n
M a t e r i a l c o d e
A =
C o n t a c t i n g
B
=
N o n - c o n -
t a c t i n g
HMS5 HMSA10 Rubber RG, V Straight RG, V B (HMSA10)
HMS4 HMSA7 Rubber R, V Straight R, V A (HMSA7)
CRW1 CRWH1 Metal +Bore-Tite
– SKFWAVE
R, V N/A
CRWA1 CRWAH1 Metal +Bore-Tite
– SKFWAVE
R, V B
CRW5 CRWA5 Metal +Bore-Tite
– SKFWAVE
R, V B (CRWA5)
CRS1 CRSH1 Metal +
Bore-Tite
– Straight R, V N/A
CRSA1 CRSAH1 Metal +Bore-Tite
– Straight R, V A
RD10 RD30 RD60 Metal – Special PTFE N/A
RD11 RD70 RD71 Metal – Special PTFE A(RD11, RD71)
RDD13 RDD14 RDD15 Fluoro-plastic/rubber
PTFE +R, V
Special PTFE N/A
7
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 8/60
8
Seals with nitrile or fluoro rubbersealing lips
HMS5 and HMSA10
The new metric radial shaft seals, HMS5 and HMSA10, are designed in accordance with ISO 6194
and DIN 3760 for use in a wide range of industrial applications.
Main features:
New optimized seal material
Spring-loaded sealing lip
Balanced sealing lip and flex section Beaded outside diameter
Auxiliary lip (type HMSA10 only)
Design
The rubber outside diameter provides optimized sealing ability in the housing, also at considerable
surface roughness or in split housings. The beads provide improved sealing ability and retention
in the bore. They also prevent spring back at installation.
The sealing lip and flex section are balanced to withstand considerable dynamic runout and
shaft-to-bore misalignment.
The auxiliary lip on type HMSA10 is non-contacting, which means that the seal type normally
can be used at the same speeds as the single-lip type HMS5, without significantly increasingtorque and underlip temperature.
Material
The new nitrile rubber compound, SKF NBR 3243, is the result of long experience and the
latest developments in seal material research at SKF. Advantages of this material include
good resistance to ageing
very good compatibility to synthetic oils
very good pumping ability
good wear resistance.
Pumping ability is defined as the time it takes for the seal to return a certain amount of oil from
the air side to the oil side. The microstructure of the SKF NBR 3243 compound results in thatthe seal rapidly pumps back the oil.
The complete range of HMS5 and HMSA10 seals is also available on request in a fluoro rubber
compound and with a stainless steel garter spring. This rubber compound has the designation
suffix V and is used in applications where temperatures exceed the limits of nitrile rubber.
HMS5
RG V
RG V
HMSA10
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 9/60
9
HMS4 and HMSA7 seals
The rubber outside diameter seals HMS4 and HMSA7 have a carbon steel reinforcing
ring and are preloaded by a garter spring. They are available in either nitrile or fluoro
rubber, primarily in inch sizes, but also in a limited metric range.
HMS4: The basic design.
HMSA7: The same design as HMS4 but with a contacting, auxiliary lip.
The HMS4 and HMSA7 seals will continually be replaced by the newly
developed HMS5 and HMSA10 seals during a transition period.
CRS seals
The metal-cased CRS seals are relatively easy to install and will, provided the housing
bore meets the accurate requirements, have a tight fit in the housing bore. They all
have a straight-edged sealing lip and a carbon steel garter spring.
CRS1: Basic type with one metal case.
CRSH1: Same as CRS1 but with an added inner case providing increased stiffness.
CRSA1: Same as CRS1 but with a contacting, auxiliary lip for increased exclusion
capabilities.
CRSHA1: Designed with an auxiliary lip and reinforced by an inner metal case.
All CRS seals are available with sealing lips made of either nitrile or fluoro rubber
and are stocked in a wide range of sizes.
HMSA7
CRS1 CRSA1
CRSH1 CRSHA1
HMS4
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 10/60
10
Low-friction seals with SKF WAVE lip design
The seal types CRW1, CRWH1, CRWA1 and CRWHA1 have an SKF WAVE lip design
to reduce friction and heat generation. The sinusoidal form of the SKF WAVE lip con-
siderably extends the path on the counter surface and reduces the radial load against
the shaft. The metal outside diameter simplifies installation and provides a tight fit
in the housing bore.
The outside diameter of the seals is coated with Bore-Tite, a non-hardening, water-
based acrylic sealant that enables the seals to accommodate small imperfections in
the housing bore surface to improve sealing performance.
The CRW seals are primarily designed for lubricant retention but the types CRWA1
and CRWHA1 are also suitable for exclusion of dust and light contaminants.
CRW1 has a single metal case, a hydrodynamically formed SKF WAVE lip and
a carbon steel garter spring.
CRWH1 has the same features as CRW1 but adds a double metal case.
CRWA1 has a single metal case, a hydrodynamically formed SKF WAVE seal lip,
a carbon steel garter spring and a non-contacting, auxiliary lip.
CRWHA1 has the same design as CRWA1 but adds a double metal case.
All CRW seals are available in either nitrile or fluoro rubber.
oil side air side
Conventional
sealing lip with
straight edge
oil side air side
SKF WAVE lip
with sinusoidal
edge
CRWH1
Pressure profile SKF WAVE lip designs
The seal types CRW5 and CRWA5 with a pressure profile SKF WAVE lip design are
appropriate for applications where pressure differentials across the seals are higherthan normal. They are easy to install and provide a firm and accurate seating in the
housing bore. The seals are coated with Bore-Tite on their outside diameter.
The seals are primarily intended for lubricant retention, but type CRWA5 is equipped
with a non-contacting, auxiliary lip to exclude dust and light contaminants. CRW5 and
CRWA5 are available in nitrile and fluoro rubber.
CRW5 has a pressure profile SKF WAVE lip, a carbon steel garter spring and a metal case.
CRWA5 has the same design as the CRW5 but adds a non-contacting, auxiliary lip.
Note: Where there is a pressure differential across the seal, the seal should be secured
axially in the housing bore.
CRW1
CRWA5CRW5
CRWHA1CRWA1
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 11/60
11
Series RD
Seals in the RD series, with sealing lip(s) made of PTFE, are protected by a metal case and one or two additional inner cases.
They are designed to withstand aggressive environments, high temperatures, high pressures and dry running of the sealing
lip(s). These PTFE radial shaft seals are available in several variants. The metal case can be made of aluminium, carbon steel
or stainless steel. Different PTFE compounds are used for the sealing lips, including materials conforming to US Food and
Drug Administration (FDA) regulations. The nominal dimensions of the PTFE radial shaft seals are in accordance with ISO
6194/1:1982 and DIN 3760-1996, which makes them interchangeable with traditional radial shaft seals in existing applica-tions.
Series RDD
Seals in the RDD series are designed without a metal case and are intended for use in the food industry. They withstand
aggressive environments, low temperatures, high pressures and dry running of the sealing lip(s). An O-ring in a groove on
the outside diameter of the seal provides excellent static sealing ability. The O-ring material can be selected to meet different
operating conditions. RDD seals have the same nominal dimensions as the metal-cased RD designs.
Both series are manufactured on demand.
RD60
RD71 RDD13 RDD14 RDD15
RD70RD11 RD30RD10
Seals with PTFE sealing lips
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 12/60
Radial shaft seals
Large diameter sealsHeavy industries, such as metal, construction, wind energy, forestry, mining and pulp and paper, provide a challenging
environment for large diameter radial shaft seals. Operating within a wide range of speeds, temperatures and environmen-
tal conditions, these seals are expected to reliably retain lubricants while preventing harsh contaminants from entering thesystem.
Generally, seals for shaft diameters larger than 203 mm (8 in) are known as large diameter seals. SKF large diameter seals
are available in a wide range of designs and materials to meet the demands of each challenging application. The range
includes
Metal-cased seals
Rubber outside diameter seals
- metal-inserted
- fabric-reinforced
- all-rubber
The different designs are generally suitable for applications shown in the table below.
Large diameter seals applications
Application General machineryIndustrial gearboxes
Rolling mills, metalHot strip millsCold rolling millsIndustrial gearboxes
Industrial gearboxesGeneral machineryRolling mills, paper mills
Special machineryCrushers, shredders,bailers etc.
Type General purpose Water/scale exclusion High speed
> 25,4 m/s> 5 000 ft/min
High Dynamic Runout(DRO) or Shaft-To-BoreMisalignment (STBM)
HDS1-3, HDSD-E 3 2 x 2
HDS4, 6 2 2 3 2HDS7 2 3 x x
HDSA, B, C 3 2 x 3
HDL 2 2 3 3
HS4-8 2 x 2 3
SBF, HSF 3 1 x x
1 = Good solution 2 = Better solution 3 = Best solution x = Not recommended
12
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 13/60
13
Metal-cased sealsHDS7
The highly engineered HDS7, developed by SKF primarily for grease
lubricated applications, provides enhanced exclusion capabilities. It features
an optimized, springless lip profile that aggressively pumps contaminants
away from the lip, making it an excellent choice for heavily contaminated
environments such as rolling mill applications, where water and scale are
present. The springless lip design of the HDS7 also reduces the radial load
that can lead to increased seal wear and elevated underlip temperature.
The HDS7 seal can also be equipped with an auxiliary lip made of PTFE
and/or an elastomer applied to the metal outside diameter, see “Additionaldesign options” on page 16.
Type HDS7 is available on a made-to-order basis in the sealing lip mater-
ials nitrile rubber for common use, Duralip for improved abrasion resist-
ance and SKF DURATEMP that combines improved abrasion resistance
with increased temperature capability.
HDL seals
The HDL seals are premium metal-cased radial shaft seals for oil reten-
tion. They are specially designed for severe operating conditions like highspeeds and temperatures, high run-out and high misalignment.
The HDL seals feature a stainless steel garter spring combined with
individual stainless steel finger springs around the entire circumference
of the seal. The spring combination helps the seal maintain high sealing
ability also under severe service conditions.
Type HDLA is equipped with a non-contacting, auxiliary lip for extra
protection against contaminants.
All HDL seals are available in the sealing lip materials nitrile rubber,
hydrogenated nitrile rubber and fluoro rubber.
HDS7
HDL
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 14/60
14
HDS1, HDS2 and HDS3
The HDS1, HDS2 and HDS3 seals are the most commonly used metal-cased seals,
designed for general purpose applications. They are designed with a heavy-duty metal
case and a stainless steel garter spring.
HDS1 has its spring installed in a protective SKF Springlock groove that encloses some
270° of the spring.
HDS2 adds an SKF Springcover that locks the spring in the groove. HDS2 is recom-
mended for blind installations where spring displacement may go undetected.
HDS3 has the same features as the HDS2 but adds adjustable spacer lugs.
All of them can also be equipped with an auxiliary lip made of PTFE and/or an elastomer
applied to the metal outside diameter, see “Additional design options” on page 16.
The seals are manufactured on a made-to-order basis and are available in nitrile rubber,
Duralip, SKF DURATEMP or LongLife. Nitrile rubber is the standard material for HDS1
and HDS2 while Duralip is the standard material for HDS3.
HDS3
HDS2HDS1
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 15/60
15
HDSA, HDSB and HDSC
These seals are designed with an elastomeric auxiliary lip in addition to the sealing
lip. They are intended for use in highly contaminated applications where axial space
is insufficient for more than one seal.
HDSA: The chamfer of the auxiliary lip faces the sealing lip, allowing easier shaft
installation from the direction of the sealing lip.
HDSB: The chamfer of the auxiliary lip faces away from the sealing lip, allowing
easier shaft installation from the back but with the downside of somewhat reduced
exclusion ability compared to the HDSA seals.
HDSC: The auxiliary lip is located in front of the sealing lip with its chamfer facing
the same direction as the sealing lip to provide maximum exclusion ability.
All of them are available with an SKF Springcover (HDSA2, HDSB2 and HDSC2)or without an SKF Springcover (HDSA1, HDSB1, HDSC1).
These seals can also be equipped with an elastomer applied to the metal outside
diameter, see “Additional design options” on page 16.
The HDSA, HDSB and HDSC seals are available on a made-to-order basis in nitrile
rubber, Duralip, SKF DURATEMP or LongLife.
HDSA HDSB
HDSC
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 16/60
16
HDSD and HDSE
These seals have a robust double metal case and are equipped with two sealing
lips providing highly efficient protection against both liquid and solid contaminants.
HDSD seals are designed with the two sealing lips facing opposite directions.
They are used for applications requiring the separation of two fluids.
HDSE seals have two sealing lips facing the same direction. They are used
where a back-up seal is needed for additional retention ability.
The HDSE seals can also be equipped with an auxiliary lip made of PTFE, see
“Additional design options” on page 16.
All of them are available with an SKF Springcover (HDSD2, HDSE2) or without
an SKF Springcover (HDSD1, HDSE1). They are available on a made-to-orderbasis in nitrile rubber, Duralip, SKF DURATEMP or LongLife.
When using an HDSD or HDSE seal, it is very important to provide a means to
lubricate the sealing lips, i.e. the cavity between the sealing lips must be packed
with grease or the seal supplied with lubrication holes drilled from the outside
diameter into the cavity between the lips.
Additional design options
The HDS1, HDS2, HDS3, HDS7 and HDSE seals can also be equipped with a PTFE
auxiliary lip to further protect the bearing and sealing lips against dust particles in
heavily contaminated environments. And, the PTFE lip can be positioned and directed
to provide additional lubricant retention. The PTFE lip is clamped between the metal
case and the rubber seal body without significantly increasing the total seal width.
It can withstand wear, chemical attack and dry running and offers improved seal
performance with only a minimum of friction torque.
The HDS1, HDS2, HDS3, HDS7 seals are also available with an elastomer appliedto the outside diameter for use in applications with bore temperatures up to 100 °C
(210 °F). The elastomer accommodates imperfections in the housing bore surface,
improving service life and performance of both seal and equipment. The rubber out-
side diameter also reduces the risk of damage to the housing during installation and
removal.
For more information on these design options, please refer to the publication “Large
diameter seals“.
HDSD2
HDSE1
HDSD1
HDSE2
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 17/60
17
Seals in the HSF series have a strong, flexible fabric-reinforced rubber back instead of a metal case. Their conventional seal-
ing lip is preloaded by a stainless steel garter spring that is positioned in an SKF Springlock groove. The HSF seals are avail-
able in solid or split versions and are intended for use in heavy-duty applications such as gear drives, propeller shafts, cold
and hot mill work rolls, pumps, paper machinery, etc.
The HSF series consists of the HSF5, HSF6, HSF7 and HSF8 solid seal types and their split versions HSF1, HSF2, HSF3 and HSF4.
HSF5 is the standard single-lip designHSF6 adds radial lubrication grooves on the back of the seal
HSF7 adds a circumferential lubrication groove
HSF8 offers a contacting, auxiliary lip to the standard HSF5 design
The HSF1, 2, 3 and 4 are the split versions of the solid types listed above. There is also a pressure profile type, HSF9, in solid
version only. All versions have a threaded spring connection as standard.
All HSF seals are finished oversize to the housing to allow proper compression and stability. A cover plate is required to prop-
erly install and apply all HSF seal types. The plate creates an axial preload to provide reliable static sealing performance. The
plate should also be designed to avoid seal distortion during installation.
The HSF seal series is available in nitrile and fluoro rubber.
Fabric-reinforced sealsHSF1 HSF2 HSF3 HSF4
HSF7 HSF9HSF8
HSF5
HSF6
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 18/60
18
Metal-inserted sealsSBF
The SBF seal is designed with a moulded-in, flexible metal stiffening ring eliminating
the need of a cover plate. A stainless steel garter spring is positioned in the SKF
Springlock groove and an optional SKF Springcover is available.
Type SBF can be used as an upgrade to fabric-reinforced seals in many applications
that are either grease or oil lubricated.
SBF seals are available in both nitrile and fluoro rubber.
HDS4 and HDS6
HDS4 and HDS6 seals are designed with an L-type sheet steel reinforcement ring
and 12,7 mm (0.5 in) spacer lugs moulded into the seal body. The lugs can be
trimmed or removed if necessary.
HDS4 features a patented moulded-in garter spring that cannot be displaced
during difficult installations. The HDS4 provides very good sealing performance
in oil lubricated applications.
HDS6 is a springless version of the HDS4 for grease retention and contaminant
exclusion.
Nitrile rubber is standard for both the HDS4 and HDS6, but they are also available
in Duralip, SKF DURATEMP and LongLife.
SBF
HDS6
HDS4
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 19/60
19
All-rubber sealsHS5HS4 HS6 HS7 HS8
All-rubber seals in the HS series are available either solid or split and do not contain any metal or
fabric reinforcement. The actual seal is finished oversize to the housing to allow proper compres-
sion and stability. A cover plate is required to compress the seal within the cavity, helping stabilize
the seal, close the split joint and prevent leakage.
A garter spring provides the radial load against the shaft.
HS4 is a solid seal with a spring positioned in the SKF Springlock groove. It is recommended for
both vertical and horizontal shafts.
HS5 has the same design as the HS4 with the addition of an SKF Springcover for added protec-tion against spring pop-out during handling and installation and against contaminants.
Where shaft removal is impractical, the split versions of the HS series are an excellent choice. They
are simply placed around the shaft and pushed into the seal bore, then held firmly by a cover plate
that compresses the split joint together. HS split seals perform best with grease or heavy lubricants
but can also be used with light lubricants if the level is kept well below the shaft centre line, par-
ticularly at higher surface speeds.
HS6 is designed with a spring-loaded sealing lip and an SKF Springlock groove. HS6 features a
separate, loose garter spring with a hook-and-eye spring connection unless otherwise specified.
HS7 has a spring-loaded sealing lip for grease lubrication only and is equipped with both an SKF
Springlock groove and an SKF Springcover. A control-wire spring connector is used to join the
seal ends together. This unique design simplifies installation but does not provide the same highsealing performance as other seals in the HS series.
HS8 is designed with a spring-loaded sealing lip, SKF Springlock groove, SKF Springcover and
a hook-and-eye spring connector. The spring is entirely enclosed except for a small portion on
either side of the split. HS8 provides the most effective sealing performance of all the split types
and is the preferred design for retaining low viscosity lubricants and excluding water. HS8 seals
perform best on horizontal shafts, but may also be used on vertical shafts if not flooded with
lubricant.
The HS series is available in both nitrile and fluoro rubber materials.
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 20/60
20
Large diameter radial shaft seals,permissible operating conditions
Standard design(preferred design)
Other basic designs Materialcode
Operating temperature range
°C °F
HDS7 HDS6
RDH
–40 to +100–40 to +100–40 to +150
–40 to +210–40 to +210–40 to +300
HDL HDLA
R
HV
–40 to +100
–40 to +150–40 to +200
–40 to +210
–40 to +300–40 to +390
SBF
RV
–40 to +100–40 to +200
–40 to +210–40 to +390
HDS2 HDS1 HDS3 HDS4
RDHV
–40 to +100–40 to +100–40 to +150–40 to +200
–40 to +210–40 to +210–40 to +300–40 to +390
HDSA2 HDSA1 HDSB2 HDSB1 HDSC2 HDSC1
RD
HV
–40 to +100–40 to +100
–40 to +150–40 to +200
–40 to +210–40 to +210
–40 to +300–40 to +390
HDSE2 HDSE1 HDSD2 HDSD1
RDHV
–40 to +100–40 to +100–40 to +150–40 to +200
–40 to +210–65 to +210–40 to +300–40 to +390
HS solid HS5 HS4
RDHV
–40 to +100–40 to +100–40 to +150–40 to +200
–40 to +210–40 to +210–40 to +300–40 to +390
HS split HS8 HS6 HS7
R
DHV
–40 to +100
–40 to +100–40 to +150–40 to +200
–40 to +210
–40 to +210–40 to +300–40 to +390
HSF solid HSF5 HSF6 HSF7 HSF8 HSF9
RV
–40 to +100–40 to +200
–40 to +210–40 to +390
HSF split HSF1 HSF2 HSF3 HSF4
RV
–40 to +100–40 to +200
–40 to +210–40 to +390
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 21/60
21
Pressuredifferential
Coaxiality
mm (in)
Runout(Dynamiceccentricity ofshaft)
mm (in)
Maximum shaftsurface speed
m/s (ft/min)
Ease of installation
Ability to seal low viscositylubricants and exclude water
0 1,6(0.062)
2,4(0.093)
25 (>5 000)depending on theoperating conditions
Excellent Highly effective exclusion of waterand solid contaminants and excellentretention of grease.
0,1
(15)
2,5
(0.1)
2,4
(0.093)
24 (>4 700)
25 (>5 000)35 (>7 000)
Good Excellent, including retention of light oils
at high surface speeds and misalign-ment.
0,1(15)
1,5(0.06)
2,4(0.093)
25 (>5 000) Excellent Excellent for oil or grease retention.
0,1(15)
1,6(0.062)
2,4(0.093)
25 (>5 000) HDS2, HDS3,HDS4:ExcellentHDS1:Good
Excellent for oil or grease retention.
0,1(15)
1,6(0.062)
2,4(0.093)
25 (>5 000) Excellent to good,varies with
equipment design.
HDSA/B: Excellent for oil or greaseretention with exclusion of light to mod-
erate contamination.HDSC: Good grease retention, increasedprotection against contamination.
0,1(15)
1,6(0.062)
2,4(0.093)
25 (>5 000) HDSD2, HDSE2:ExcellentHDSD1, HDSE1:Good
HDSD: Excellent for oil or grease reten-tion and exclusion of light to moderatecontamination or separation of twomedia.HDSE: Good grease retention, increasedprotection against contamination.
0,07(11)
1,6(0.062)
2,4(0.093)
HS4: 15 (3 000) HS5: 13 (2 500)
HS4: GoodHS5: Good
HS4: GoodHS5: Good
0
1,6
(0.062)
2,4
(0.093)
HS6: 10 (2 000)
HS7: 7,5 (1 500)HS8: 10 (2 000)
HS6: Fair
HS7: ExcellentHS8: Good
HS6, HS8: Good to excellent for oil
or grease retentionHS7: Good (grease only)
0,03(5)
1,5(0.06)
2,4(0.093)
15 (>3 000)depending on theoperating conditions
Good to excellent
Excellent
0 1,5(0.06)
2,4(0.093)
15 (>3 000)depending on theoperating conditions
Fair to gooddepending on theavailable spacefor installation
Good to excellent
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 22/60
Radial shaft seals
Cassette seals and shaftsealing units
Cassette seals and sealing units are intended for use in heavy-duty applications such
as off-road vehicles, agricultural or similar construction machinery where environ-
mental and operating conditions are harsh. These seals represent the increased
complexity of sealing technology when compared with standard sealing solutions.
The geometry of cassette seals provides optimum protection against water, dust, mudand other contaminants. This improved protection is the result of the special radial
and axial sealing lips, unitized with axial and radial wear sleeves. Cassette seals elimi-
nate the need to machine the shaft prior to seal replacement.
SKF cassette seals and sealing units are tailored to the customer’s specific installation
requirements as well as to the specific operating conditions.
22
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 23/60
23
SKF Mudblock cassette seals
SKF Mudblock cassette seals are a new generation of radial shaft sealing units specifically devel-
oped for heavy-duty applications in harsh environments and difficult operating conditions.
SKF Mudblock cassette seals are customized sealing solutions that have the following options:
Spring-loaded primary sealing lip
Auxiliary sealing lips Wear sleeves
Rubber-covered outside surfaces
They can be made from a variety of elastomeric materials, including nitrile and fluoro rubber.
The geometry of SKF Mudblock cassette seals has been optimized to provide excellent retention
of either grease or oil and maximum protection against liquid or solid contaminants.
MUD1 MUD2 MUD5MUD3
MUD6
MUD4
MUD7
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 24/60
24
SKF SCOTSEAL sealing unitsAn SKF SCOTSEAL is a customized sealing unit that is designed to retain lubricants
and exclude contaminants in hub bearing arrangements, typically found on the
axles of commercial and off-road vehicles. There are three different SKF SCOTSEAL
designs:
SKF SCOTSEAL Classic: Unitized one-piece seal consisting of a metal-inserted seal-
ing element and a metal case. The sealing element is designed with one spring-
loaded sealing lip that seals against the metal case and two auxiliary lips that
exclude contaminants. The metal case has a Bore-Tite coated outside diameter
and protects the sealing lips from being damaged during installation. The unit is
press fit into the hub bore using SKF SCOTSEAL installation tools. SKF SCOTSEAL
Classic sealing units are proven solutions for heavy-duty applications.
SKF SCOTSEAL Longlife: Unitized one-piece seal consisting of a metal-inserted
sealing element and a metal case. The sealing element is designed with one spring-
loaded sealing lip that seals against the metal case and three auxiliary lips that
exclude contaminants. The metal case has a Bore-Tite coated outside diameter
and protects the sealing lips from being damaged during installation. The unit is
press fit into the hub bore using SKF SCOTSEAL installation tools. SKF SCOTSEAL
Longlife sealing units are robust solutions with excellent synthetic lubricant reten-
tion properties and high resistance to dirt ingress even at high temperatures.
SKF SCOTSEAL Plus XL: The most advanced SKF SCOTSEAL design consisting of
a metal-inserted sealing element and a metal case with a rubber outside diameter.
The sealing element is designed with one spring-loaded sealing lip that seals againstthe metal case and three contacting auxiliary lips that exclude contaminants. SKF
SCOTSEAL Plus XL sealing units are robust solutions with excellent synthetic lubri-
cant retention properties and high resistance to dirt ingress even at high tempera-
tures. They are easy to install and require no installation tool.
SKF SCOTSEAL Plus XL
SKF SCOTSEAL Classic SKF SCOTSEAL Longlife
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 25/60
Wear sleevesFor radial shaft seals to perform efficiently, the condition of the counterface, i.e. shaft
surface, is of significant importance. If the counterface is worn or damaged, the seals
will not be able to fulfil their function; to retain lubricant and exclude contaminants.
SKF wear sleeves have been developed to easily solve the problem of worn seal
counterfaces. They are simply pushed over the damaged surface, allowing the shaft
to be re-used within minutes and at a fraction of the cost of traditional reworking.
SKF wear sleeves are available in two different designs:
SKF SPEEDI-SLEEVE: Very thin-walled wear sleeve, 0,28 mm (0.011 in), thatallows the same size seal as the original to be used. The SKF SPEEDI-SLEEVE
range consists of the standard version for normal operating conditions and the
SKF SPEEDI-SLEEVE Gold for harsh operating conditions. They are available for
shaft diameters up to approx. 200 mm (8 in).
Large diameter wear sleeves (LDSLV): Wear sleeves with a 2,39 mm (0.094 in)
wall thickness for shaft diameters greater than 200 mm (8 in) up to approximately
1 150 mm (45 in). Two types are available on demand; the LDSLV3 with a flange
and the flangeless LDSLV4.
25
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 26/60
Axial shaft sealsMost axial shaft seals, like V-ring seals, are relatively simple sealing elements that are typically
used as secondary seals in applications where the primary seals are subjected to large quantities
of contaminants.
Axial shaft seals are available from SKF as
V-ring seals
Metal-cased V-type sealing rings and axial clamp seals Mechanical seals
With the exception of axial clamp seals, axial shaft seals rotate with the shaft and act as slingers.
They tolerate small misalignments of the shaft with respect to the counterface and provide reliable
sealing performance even if the shaft is out of round or rotates eccentrically.
26
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 27/60
27
V-ring sealsV-ring seals are unique all-rubber seals for rotating shafts. They consist of a body and a conical
shaped sealing lip that is joined to the body by means of a resilient “hinge”.
All V-rings are installed on and rotate with the shaft. Their lips seal axially against a counterface
that is perpendicular to the shaft. The body has an interference fit on the shaft and holds the lip
in position. V-rings can be stretched to fit over a flange during installation, which is a very valuable
characteristic, especially in the case of seal replacement. They can operate at sliding velocities up
to 8 m/s (1 575 ft/min). At velocities above 8 up to 12 m/s (1 575 to 2 362 ft/min) V-rings must
be axially located.
V-rings are used both to exclude water spray and solid contaminants, fig. a below, and to retain
lubricants, fig. b. They can also act as a grease valve, fig. c.
V-ring seals are available in a wide variety of designs and sizes to fit the requirements of most
applications. V-rings are normally made of nitrile rubber. For applications where higher tempera-
tures occur, V-rings made of fluoro rubber should be used.
a b c
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 28/60
28
Design VR1 VR2 VR3 VR4 VR5 VR6
min (mm) 2,7 4,5 105 300 450 300
min (in) 0.106 0.177 4.134 11.811 17.716 11.811max (mm) 2 020 210 2 025 2 010 2 010 1 995
max (in) 79.257 8.268 79.724 79.134 79.134 78.543
VR1 VR2 VR3 VR4 VR5 VR6
V-ring seals are available in four standard designs and two large-size, heavy-duty designs;
VR1: Most common V-ring with a standard cross section and straight back-sideface.
VR2: V-ring with a standard low cross section, tapered back face and wide body, providing
a very firm hold on the shaft.
VR3: Narrow V-ring with low cross section intended for use in compact sealing arrangements
or labyrinth seals.
VR4: Wide V-ring with high cross section designed as a secondary seal for heavy-duty applica-
tions where the primary seal has to be protected from water and/or solid contaminants. This
seal permits the largest axial displacements.
VR5: Wide, large diameter V-ring with low cross section. This seal can be axially located on
the shaft using a standard clamping band. Primarily intended for large, high-speed applications,
like rolling mills and paper mills.
VR6: Heavy-duty, large diameter V-ring for applications including large axial displacements.
This seal can be axially located on the shaft using a standard clamping band. Primarily intendedfor large, high-speed applications, like rolling mills and paper mills.
SKF V-ring seals are available for shaft sizes according to table below.
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 29/60
29
MVR1 MVR2
Metal-cased V-type sealingrings and axial clamp seals Series MVR and CT
Metal-cased V-type sealing rings act as slingers and protect primary
seals from coarse contaminants, dust and water spray to considerably
extend the reliability and service life of sealing arrangements.
MVR V-type sealing rings from SKF consist of a metal case that houses
a body and a conical shaped axial sealing lip made of nitrile rubber. Thecorrosion-resistant metal case protects the elastomeric sealing lip from
contaminants. The seal has a tight fit in its seating and can accommodate
speeds up to 12 m/s (2 362 ft/min) without auxiliary clamping devices.
There are two MVR types, the basic MVR1 and the MVR2 with case
extension.
Series MVR is available for shaft diameters ranging from 10 to 200 mm
(0.394 to 7.874 in) and can be used at temperatures between –30 and
+100 °C (–20 and +210 °F).
SKF axial clamp seals are designed for large diameter shafts. They do notrotate but seal axially against a rotating counterface.
The CT axial clamp seals are made of profiled strips of non-reinforced
nitrile rubber and are held firmly in position by stainless steel band
clamps. Axial clamp seals are available for shaft diameters ranging from
150 up to 4 600 mm (6 up to 181 in) and are produced in two different
designs;
CT1: Axial clamp seal that permits axial displacement with respect
to the counterface of +2,4 mm (0.09 in).
CT4: Axial clamp seal with an extra wide body that is held in position
by two clamps. These seals can accommodate axial displacement withrespect to the counterface of +4,8 mm (0.18 in).
CT1 CT4
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 30/60
30
HDDF
Permissible operating conditions
Operating conditions Guideline values
Operating temperature, °C (°F)
continuous operation
brief periods, maximum
–50 to +100 (–60 to +210)
+120 (+250)
Peripheral speed, m/s (ft/min)
continuous operationbrief periods, maximum
up to 1,75 (345)up to 4 (790)
Pressure acting on seal, MPa (psi)
continuous operation
brief periods, maximum
up to 0,2 (30)
up to 0,35 (50)
Mechanical seals
HDDF
Mechanical seals are designed for use under severe operating conditions at relatively
low speeds. They offer reliable protection against solid and liquid contaminants as well
as retention of lubricants. These seals were originally developed for off-road vehicles
but have been found to be equally suitable for a wide range of other applications,
where effective protection is required against sand, soil, mud water, etc.
SKF mechanical seals consist of two identical sealing rings and two similar Belleville
washers (cup springs). The sealing rings are made of wear- and corrosion-resistant
steel and have finely finished sliding and sealing surfaces. The Belleville washers made
of nitrile rubber provide the necessary uniform face loading and positive sealing at thebore and outside diameters.
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 31/60
Hydraulic sealsHydraulic seals are designed to retain hydraulic fluids, exclude solid or liquid contaminants and
maintain hydraulic pressure. These tasks require a variety of different seal designs and appropriate
accessories. The SKF range of hydraulic seals is comprised of
piston seals
rod seals
wiper seals
guide rings and guide strips.
Hydraulic cylinders also require static sealing solutions like O-rings and back-up rings that are also
offered by SKF.
On the following pages the different hydraulic seals are presented with a short description.
Comprehensive technical product data can be found in the technical catalogue “Hydraulic seals”.
In addition to hydraulic seals, SKF also manufactures components for use in pneumatic cylinders.
For additional information about these products, please contact your local SKF representative.
Hydraulic cylinder – terminology
Rod end
Rod seal
Wiper seal Cylinder tubeGuide ring Cylinder bottom Plain bearingPistonStatic seal
Guide ringPistonsealStatic seal Rod
31
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 32/60
SKF hydraulic seals material
Composition of basic material Designation according to
SKF IS0 1629 / ASTM1) D1418
Acrylonitrile-butadiene rubber (nitrile rubber) N NBR
Hydrogenated acrylonitrile-butadiene rubber HN HNBR
Fluoro rubber F FKM
Polytetrafluoroethylene PTFE PTFE
Polyurethane PUR PUR
Phenolic/fabric PF PF
Acetal resin A POM
Polyamide PA PA
Ethylene propylene diene monomer E EPDM
Ultra-high molecular weight polyethylene PE-UHMW PE-UHMW
Silicone rubber Q VMQ
Perfluoroalkoxy PFA PFA
Thermoplastic polyester elastomer HY TCP-ET
1) American Society for Testing and Materials
Hydraulic seals
Material overviewThe seal material has a significant impact on seal performance and reliability. To meet the needs
of different applications, SKF hydraulic seals are produced in a variety of materials (see table below).
The materials have individual properties that make them particularly suitable for specific applications.
The codes used to identify the seal material of SKF hydraulic seals are listed in the table below.
The codes also appear in some seal designations.
Details about the physical properties and chemical resistance of each seal material in operation
can be provided by your SKF representative.
32
IMPORTANT SAFETY NOTE: At temperatures above +300 °C (+570 °F), all fluoro elastomersand PTFE compounds give off dangerous fumes. If there is unintentional contact with yourskin or if the vapours have been inhaled, a doctor should always be consulted.
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 33/60
Hydraulic seals
Piston sealsThe main function of a piston seal is to provide enough tightness in order to maintain
the hydraulic pressure necessary to make the piston move. However, the piston seal
must still allow a certain oil film to minimize friction and wear.
Choosing the appropriate piston seal for a given application is primarily dependent on
how the cylinder operates. For cylinders that are exclusively single-acting, it is always
best to choose a seal designed to provide optimum sealing qualities for single-acting
functions with the thinnest possible lubrication film that can pass through the contact
area between the seal and the cylinder tube surface.
A double-acting seal should be selected for a double-acting cylinder. A double-acting
piston with two single-acting seals will typically result in premature seal failure. This
is because very high pressure can be trapped between the seals causing them to blow
out.
This catalogue describes both single- and double-acting piston seals with their main
design features and operating capabilities. For comprehensive technical data and
recommendations regarding proper seal selection, as well as for information about
machining and installation, please see the technical catalogue “Hydraulic seals”.
33
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 34/60
34
Double-acting piston seals type CUT consist of a step-cut slide ring of
polyamide and a rectangular energizer of nitrile rubber. The material ofthe slide ring provides low friction even at high pressure and is very wear
and extrusion resistant. The cut slide ring is very easy to install, even into
a closed housing groove. The energizer offers excellent static sealing ability
in the seal housing groove.
Type CUT is designed for use in heavy-duty hydraulic applications, mainly
in double-acting cylinders with pressures up to 50 MPa (7 252 psi), short-
term 100 MPa (14 504 psi), also at radial clearances of up to 0,5 mm
(0.02 in). Type CUT is also available in a specific material combination
withstanding even tougher operating conditions.
The piston seal type CUT provides a number of advantages:
Fits into existing housing designs according to ISO 7425-1
Only two parts to mount
Equilateral – cannot be installed in wrong direction
Split slide ring – no tool required
Excellent compatibility with biodegradable oils
The double-acting piston seal type GHTL consists of a central slide ring,
two support rings and one energizer. It is intended for use in hydraulic
cylinders for medium and heavy-duty applications.
The GHTL is designed with an energizer of nitrile rubber, a slide ring ofa filled PTFE material and two support rings of polyamide. The support
rings are designed with a locking function to further secure the seal‘s
position in the housing during installation. This feature also reduces the
risk of incorrect installation.
CUT
Installation example
GHTL
Installation example
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 35/60
35
MD-R
PENType PEN is a double-acting piston seal consisting of a slide ring of poly-
urethane and an energizer of nitrile rubber, enabling static sealing abilityin the housing groove. The slide ring is designed with a radius on the
static side for optimal function with the O-ring.
Type PEN is used in light- and medium-duty hydraulic applications and
can be installed into closed housing grooves without any tools.
Type URG is a double-acting piston seal consisting of a polyurethane
slide ring and a square-cut energizer of nitrile rubber. The slide ring has
chamfered sealing edges to obtain optimal tightness and resistance to
extrusion. Its notches in the radial face enable rapid response to changes
in the pressure direction.
URG seals are designed for medium-duty applications.
Double-acting piston seals type MD-R are symmetrically designed and
consist of a central sealing ring of nitrile rubber, support rings of a poly-
ester elastomer and integrated guide rings of acetal resin.
Type MD-R has rectangular guide rings providing very good quiding
performance and eliminating the risk of fatigue cracks.
The central sealing ring has three sealing edges to provide high sealing
ability both statically and dynamically.
MD-R seals are used in a wide range of light- and medium-duty applica-
tions.
URG
Installation example
Installation example
Installation example
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 36/60
36
GH
Series G and GL
All types in the series G and GL consist of a dynamically sealing slide ring made of
PTFE or other thermoplastic materials and a static, elastomeric part that functions
as an energizer. They are available in different designs and material combinations
to meet demands for low friction, small housing dimensions and long service life.
The main difference between series G and GL is the slightly lower cross section of
the GL slide ring. The basic slide ring material for series GL is unfilled PTFE, while
the basic material for series G is a bronze-filled PTFE compound.
GR GN GCGS GG
GH-XX8
The table on page 37 indicates which seal type is appropriate for different application
demands. Comprehensive technical data and selection criteria can be found in the
technical catalogue “Hydraulic seals”.
G GL GLC GLG
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 37/60
37
Features and field of application of SKF slide ring seals
GH Basic design, double-acting, chamfered edges at the dynamic outside diameter to reduce the risk of extrusion, notches
to avoid pressure build-up between slide ring and energizer.
G, GL Double-acting, sharp edges at the dynamic outside diameter, recommended for use in light- or medium-duty
hydraulic cylinders where impure media may occur.
GC, GLC Double-acting, chamfered edges at the dynamic outside diameter to reduce the risk of extrusion.
GG, GLG Double-acting, sharp edges at the dynamic outside diameter and a groove in the sliding surface for reduced friction.
GH-XX8 Double-acting, square-cut energizer providing improved load distribution against the dynamic surface.
GN Double-acting, notches in both side faces, recommended for cylinders with rapid pressure changes.
GR Double-acting, chamfered edges at the dynamic outside diameter, a groove in the sealing surface and notches in
both side faces. Additionally the slide ring has a radius on the static side for optimal function together with an O-ring.
Recommended for applications where additional rotating or slewing movements may occur.
GS Single-acting, recommended for applications with high demands on sealing ability.
Choice of material
Medium Material contact surface Slide ring material O-ring material
Hydraulic oil
Lubrication oil(mineral oil based)
Steel: min 33 HRC
Chromed surface, cast iron
1) PTFE + bronze
2) PTFE + glass fibre3) PE-UHMW
N
NN
Stainless steel, aluminium,
anodized or chromed bronze
1) PTFE + carbon
2) PTFE + carbon fibre
3) PE-UHMW
F
F
F
Water
Water/glycol
Steel: min 33 HRC
Chromed surface, cast iron,
stainless steel, aluminium,
anodized or chromed bronze
1) PTFE + carbon
2) PTFE + carbon fibre
3) PE-UHMW
N
F
FWater/oil
emulsion
Hot water /steam Steel: min 33 HRC
Chromed surface, cast iron,
stainless steel, aluminium,
anodized or chromed bronze
1) PTFE + carbon
2) PTFE + carbon fibre
E
E
Air, lubricated service
Air, non-lubricatedservice
Steel: min 33 HRC
Chromed surface, cast iron
1) PE-UHMW
2) PTFE + glass fibre3) PTFE + low-filled + colour pigment,
only lubricated service
N
NN
Stainless steel, aluminium,
anodized or chromed bronze
1) PE-UHMW
2) PTFE + carbon
3) PTFE + carbon fibre
N
N
N
More information on choice of material combinations can be found in the catalogue “Hydraulic seals”.
Features, applications and choice of material
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 38/60
38
SUA
SUD
Type SA is a single-acting, asymmetric U-ring seal made
of polyetherurethane.
SA seals are used in light- and medium-duty applications.
SA
Installation example
Seals in the SU series are single-acting PTFE seals, preloaded by stainless steel springs. They are used
as dynamic seals for slowly rotating or reciprocating movements or as static seals.
SU seals can often be used to replace rubber seals, such as an O-ring, in applications with very high or low
temperatures, non-lubricated services, demands on low friction, aggressive media, high speeds, high pressures,
vacuum etc. Series SU can be manufactured with many different spring types and in various materials to meet
specific application demands. The most commonly used SU seals are:
SUA: asymmetrical design with a wiper lip
SUD: asymmetrical design with a strong dynamic lip
SUS: symmetrical design for static applications
SUS
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 39/60
39
Seal type Seal material MaximumpressureMPapsi
Maximum linearvelocitym/sft/min
Temperaturerange°C°F
Page
CUT PA, N 50
7 250
1
200
–30 / +110
–20 / +230
34
GHTL PTFE
PA, N
40
5 800
2
395
–30 / +110
–20 / +230
34
PEN PUR, N 25
3 626
0,5
100
–30 / +90
–20 / +195
35
URG PUR, N 25
3 625
0,5
100
–30 / +90
–20 / +195
35
MD-R N, A, HY 253 625 0,5100 –30 / +100–20 / +210 35
GL, GLC, GLG PTFE 16
2 320
2
395
–30 / +110
–20 / +230
36
GC, G, GG, GN, GS,
GH-XX8, GH, GR
PTFE 25
3 625
2
395
–30 / +110
–20 / +230
36
SA PUR 25
3 625
0,5
100
–30 / +90
–20 / +195
38
SUA PTFE +
Stainless steel
25
3 625
15
2 950
–200 / +260
–330 / +500
38
SUD PTFE +
Stainless steel
25
3 625
15
2 950
–200 / +260
–330 / +500
38
SUS PTFE +
Stainless steel
25
3 625
-
-
–200 / +260
–330 / +500
38
Permissible operating conditions
Please note that the values stated above should be considered as guidelines only and not as absolute values for practical
applications.
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 40/60
40
Piston seals, selection matrixPlease select the most important factor when choosing seal design.
Then study further factors, installation instructions and dimension tables in the
technical catalogue “Hydraulic seals”.
The number 5 in the matrix represents the most appropriate design while the
number 1 represents the least appropriate.
Type/series
Material
CUT
PAN
GHTL
PTFENPA
GH
PTFEN
GL
PTFEN
PEN
PURN
URG
PURN
MD-R
NAHY
SA
PUR
Single-acting
Double-acting X X X X X X X
X
Pressure, up to 16 MPa (2 321 psi)
25 MPa (3 626 psi)
40 MPa (5 802 psi)
5
5
5
5
5
5
5
5
3
5
3
1
5
5
3
5
5
3
5
4
1
5
5
3
High temperature
Low temperature
< +110 °C (+230 °F)
> –30 °C (–22 °F)
5
5
5
5
5
5
5
5
4
4
4
4
5
4
4
3
Friction pressure = 0
pressure > 0
5
5
5
5
5
5
5
5
5
5
5
5
4
4
4
4
Surface insensitivity 5 4 4 4 5 5 4 5
Tolerance insensitivity 5 5 4 4 5 5 4 5
Ease of installation 5 3 4 4 5 5 4 5
Sealing ability pressure = 0
pressure > 0
5
5
5
5
5
5
4
4
4
3
5
5
5
5
5
5
Preferred in new designs X X X X X X
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 41/60
Hydraulic seals
Rod sealsThe rod seal is the seal in the hydraulic cylinder with the most demanding specifications. In addition to normal
wear and ageing, this seal is directly affected by irregularities on the rod surface. The rod seal is often the deci-
sive factor in the functioning of the hydraulic cylinder. Leakage through the rod seal can cause accidents and
environmental damage. Therefore, to find an optimal solution, it is extremely important to select the correct
seal and be familiar with the properties of other seal types in the rod sealing system.
The rod seal’s task is very difficult since it must seal at both high and low pressure, often in combination with
alternating high and low temperatures. The rod seal must leave a certain oil film, thin enough to return into the
cylinder after having passed an effective wiper seal. When choosing a rod seal, it is important to define the areaof application and to make selection analyses with the support of carefully defined specifications. Rod seals are
produced in several different designs in order to function under various operating conditions.
This publication presents the standard range of SKF rod seals with their main design features and operating
conditions. For comprehensive technical data and recommendations about proper seal selection, as well as for
information about machining and installation, please see the technical catalogue “Hydraulic seals”.
41
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 42/60
42
Type SIL of polyurethane is a general-purpose rod seal. This seal is designed with
an asymmetrical cross section with a short and strong dynamic sealing lip in orderto provide good sealing performance also at zero-pressure conditions. The outer seal
lip is slightly longer and slimmer than the inner lip in order to effectively seal statically
during radial and axial movements at both low and high temperatures.
Type TIL of polyurethane is designed with short and strong sealing lips providing a
good contact force towards the surface of the seal housing groove. Type TIL is more
compact than type SIL and is well suited for small radial sections, i.e. 4 to 6 mm
(0.039 to 0.236 in). This seal type retains good sealing performance under low-
or zero-pressure conditions.
The SIL and TIL seals are designed with a secondary sealing edge that reduces the
contact surface towards the rod.
TIL
SG
SIL
Installation example Installation into closed groove
Installation example
Installation into open groove
Type SG is a compact rod seal of fabric-reinforced nitrile rubber.
The integrated support ring of acetal resin prevents extrusion into the
clearance.
Type SG is designed for use in applications operating within the tem-
perature range of –30 to +100 °C (–20 to +210 °F). This seal is also an
appropriate choice for applications where a water-based hydraulic media
contains oil or glycol. In these applications, type SG can accommodate
temperatures ranging from –30 to +70 °C (–20 to +160 °F).
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 43/60
43
Type SKY is a symmetric U-ring seal of nitrile rubber, designed for
applications with small radial sections or as replacement seals for olderhydraulic equipment. The seal type is also available in fluoro rubber
on request.
Type SKY is preferably combined with a support ring of PTFE at pres-
sures over 14 MPa (2 030 psi).
Type UN is a symmetric U-ring seal of polyurethane, typically used as
replacement seal for older hydraulic equipment. For newly designed
applications, the technically more advanced SIL and TIL seals should
be used.
The SKF product range also includes accessories for rod sealing systems.
Type STR-D/A is a support ring made of acetal resin for rod seals with
the same sectional dimension as the rod seal. The support ring protects
the seal from extruding into the clearance. This allows a larger clearance,
which in turn reduces the risk of metal-to-metal contact between the
cylinder components.
The basic design is split to facilitate installation to the back-sidefaceof the seal.
SKY
Installation example
STR-D/A
Installation example
Installation example
UN
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 44/60
44
Seals in the SU series are single-acting PTFE seals, preloaded by stainless steel springs. They
are used as dynamic seals where there is slowly rotating or reciprocating movement and as staticseals.
SU seals can often be used to replace rubber seals, e.g. O-rings, in applications with very high
or low temperatures, non-lubricated services, demands for low friction, aggressive media, high
speeds, high pressures, vacuum etc. Series SU can be manufactured with many different spring
types and in various materials adjusted to the application demands. The most commonly used
SU seals are:
SUA: asymmetrical design with a wiper lip
SUD: asymmetrical design with a strong dynamic lip
SUS: symmetrical design for static applications
SUS
SUA
SUD
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 45/60
45
Series G and GL
All types in the series G and GL consist of a dynamically sealing slide ring made of PTFE or other
thermoplastic materials and a static, elastomeric part that functions as an energizer. They are avail-
able in different designs and material combinations to meet demands for low friction, small hous-
ing dimensions and long service life. The main difference between series G and GL is the slightly
lower cross section of the GL slide ring. The basic slide ring material for series GL is unfilled PTFE,
while the basic material for series G is a bronze-filled PTFE compound.
GS-XX8GNGSGRG
GLGGLCGLGGGC
The table on page 46 indicates which seal type is appropriate for different application demands.
Comprehensive technical data and selection criteria can be found in the technical catalogue
“Hydraulic seals”.
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 46/60
46
Features and field of application of SKF slide ring seals
G, GL Double-acting, sharp edges at the dynamic outside diameter, recommended for use in light- or medium-duty hydraulic
cylinders where impure media may occur.
GC, GLC Double-acting, chamfered edges at the dynamic outside diameter to reduce the risk of extrusion.
GG, GLG Double-acting, sharp edges at the dynamic outside diameter and a groove in the sliding surface for reduced friction.
GS-XX8 Single-acting, square-cut energizer providing improved load distribution against the dynamic surface.
GN Double-acting, notches in both side faces, recommended for cylinders with rapid pressure changes.
GR Double-acting, chamfered edges at the dynamic outside diameter, a groove in the sealing surface and notches in
both side faces. Additionally the slide ring has a radius on the static side for optimal function together with an O-ring.
Recommended for applications where additional rotating or slewing movements may occur.
GS Single-acting, recommended for applications with high demands on sealing ability.
Choice of material
Medium Material contact surface Slide ring material O-ring material
Hydraulic oil
Lubrication oil
(mineral oil based)
Steel: min 33 HRC
Chromed surface, cast iron
1) PTFE + bronze
2) PTFE + glass fibre
3) PE-UHMW
N
N
N
Stainless steel, aluminium,anodized or chromed bronze 1) PTFE + carbon2) PTFE + carbon fibre
3) PE-UHMW
FF
F
Water
Water/glycol
Steel: min 33 HRC
Chromed surface, cast iron,
stainless steel, aluminium,
anodized or chromed bronze
1) PTFE + carbon
2) PTFE + carbon fibre
3) PE-UHMW
N
F
FWater/oil
emulsion
Hot water /steam Steel: min 33 HRC
Chromed surface, cast iron,
stainless steel, aluminium,
anodized or chromed bronze
1) PTFE + carbon
2) PTFE + carbon fibre
3) PTFE + carbon
E
E
E
Air, lubricated service
Air, non-lubricated
service
Steel: min 33 HRC
Chromed surface, cast iron
1) PE-UHMW
2) PTFE + glass fibre
3) PTFE + low-filled + colour
pigment, only lubricated service
N
N
N
Stainless steel, aluminium,
anodized or chromed bronze
1) PE-UHMW
2) PTFE + carbon
3) PTFE + carbon fibre
N
N
N
More information on choice of material combinations can be found in the catalogue “Hydraulic seals”.
Features, applications and choice of material
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 47/60
47
Seal type Seal material MaximumpressureMPapsi
Maximum linearvelocitym/sft/min
Temperaturerange°C°F
Page
SIL
PUR 405 800
0,5100
–30 / +90–20 / +195
42
TIL PUR 405 800
0,5100
–30 / +90–20 / +195
42
SG N, A 253 625
0,5100
–30 / +100–20 / +210
42
SKY N 142 030
0,5100
–30 / +100–20 / +210
43
SKY +
support ring
N + PTFE 25
3 625
0,5
100
–30 / +100
–20 / +210
43
UN
PUR 405 800
0,5100
–30 / +90–20 / +195
43
STR-D/A A 405 800
0,5100
–30 / +100–20 / +210
43
SUA PTFE +Stainless steel
253 625
152 950
–200 / +260–330 / +500
44
SUD PTFE +Stainless steel
253 625
152 950
–200 / +260–330 / +500
44
SUS PTFE +Stainless steel
253 625
152 950
–200 / +260–330 / +500
44
GL, GLC, GLG PTFE, N 162 320
2395
–30 / +100–20 / +210
45
GC, G, GG, GN,GS, GS-XX8, GR
PTFE, N 253 625
2395
–30 / +100–20 / +210
45
Permissible operating conditions
Please note that the values stated should be considered as guidelines only and not as absolute values for practical
applications.
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 48/60
48
Type/series
Material
SIL
PUR
TIL PUR
UN PUR
GS
PTFEN
SG
NA
SKY
N
GL
PTFEN
Pressure, up to 16 MPa (2 321 psi)
25 MPa (3 626 psi)
40 MPa (5 802 psi)
5
5
4
5
5
4
4
3
2
5
5
4
5
5
4
4
2
0
5
3
1
High temperature
Low temperature
< +110 °C (+230 °F)
> –30 °C (–22 °F)
4
5
4
5
4
3
5
5
5
4
5
4
5
5
Friction pressure = 0
pressure > 0
4
4
4
4
4
3
5
5
3
3
5
4
5
5
Surface insensitivity 5 5 5 3 3 3 3
Tolerance insensitivity 5 5 5 4 5 4 4
Service life 5 5 5 4 4 3 4
Ease of installation 5 5 5 3 4 5 3
Sealing ability pressure = 0
pressure > 0
4
5
4
5
3
4
4
4
5
4
5
5
4
3
Preferred in new designs X X X
Rod seals, selection matrix
Please select the most important factor when choosing seal design.
Then study further factors, installation instructions and dimension tables in the
technical catalogue “Hydraulic seals”.
The number 5 in the matrix represents the most appropriate design while the
number 0 represents the least appropriate.
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 49/60
Hydraulic seals
Wiper sealsContaminants in the hydraulic system are the most common cause of breakdowns
and premature seal failure. The majority of contaminants enter the system through
the rod. The wiper seal’s purpose is to prevent this.
The wiper seal is the most underrated seal in the hydraulic cylinder relative to its
importance. The selection of a wiper seal should be based on the same carefully
defined specifications as the selection of piston and rod seals. The surrounding
environment and service conditions must be taken into special consideration.The
wiper seal should be designed not only to fit the rod (dynamic function) but also
to seal in the housing groove (static function).
This publication presents the standard range of SKF wiper seals with their main
design features and operating conditions. For comprehensive technical data and
recommendations about proper wiper seal selection as well as for information about
machining and installation, please see the technical catalogue “Hydraulic seals”.
49
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 50/60
50
Type PA is a single-acting wiper seal made of polyurethane with a metal
case for press fit installation. Thanks to the design of the wiper lip andthe specifically chosen material, a high and durable contact force is achieved.
The metal case provides a very high rigidity close to the bottom of the
housing for optimal fixation. Type PA is a very effective wiper seal type
for demanding applications.
Type PAK is a single-acting wiper seal made of polyurethane with a
metal case for press fit installation. Unlike type PA, type PAK has the
same width as the housing groove, which enables this type to also seal
bushings.
Type PAD is a double-acting wiper seal made of polyurethane with a
metal case for press fit installation. Thanks to its U-shape it also has
a sealing function to further reduce the oil transport passing the rodseal. Type PAD is designed for heavy-duty applications. Type PAD can
be complemented with a retainer ring to withstand very tough service
conditions.
Metal-cased wiper seal types are intended for installation into open
housings.
PA
PAK
PAD
Installation example
Installation example
Installation example
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 51/60
51
For less demanding applications, metal-cased wiper seals made of an elastomeric
material, normally nitrile rubber 80° IRH, are used.
Type GA is a metal-cased, single-acting wiper seal made of nitrile rubber for press fit
installation. Type GA can also be manufactured of fluoro rubber on request. Type GA
is used in light- or medium-duty applications.
Type SCB is a double-acting, metal-cased wiper seal made of nitrile rubber for press
fit installation. Type SCB can also be made of fluoro rubber on request. Type SCB is
used in medium-duty applications, but can be combined with a retainer ring to with-
stand even tougher conditions.
Installation exampleInstallation example
Type PO2 is a double-acting PTFE wiper seal with an energizing O-ring made ofnitrile rubber providing the static sealing function. The O-ring is also available in other
rubber materials, e.g. fluoro rubber.
Type PO is a single-acting PTFE wiper seal with an energizing O-ring made of nitrile
rubber providing the static sealing function. The O-ring is also available in other rub-
ber materials, e.g. fluoro rubber.
Both types are designed for use in applications with aggressive media, high tempera-
tures or specific demands for low friction. For newly designed applications, type PO2
is preferable.
Installation exampleInstallation example
PO2 PO
SCBGA
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 52/60
52
Type PWY is a single-acting wiper seal made of polyurethane to be installed into closed housings.
This type has an outward-directed sealing lip that rests against the retainer diameter to provide
improved static sealing ability in the housing. The wiper body is also equipped with radial ridges
to prevent the wiper seal from being distorted.
Type PWB is a single-acting wiper seal made of polyurethane to be installed into closed housings.
This type has an axial static sealing edge on the front face of the wiper body to keep it in place in
the housing and axial ridges on the inside diameter to prevent the wiper seal from being distorted.
PWY
PWB
Installation example Installation example
Seal type Seal material Maximum linearvelocitym/sft/min
Temperaturerange°C°F
Page
PA PUR 2395
–30 / +90–20 / +195
50
PAK PUR 2395
–30 / +90–20 / +195
50
PAD PUR 2395
–30 / +90–20 / +195
50
GA N 2395
–30 / +100–20 / +210
51
SCB N 2395 –30 / +100–20 / +210 51
PO2 PTFE, N 152 950
–40 / +110–40 / +230
51
PO PTFE, N 152 950
–40 / +110–40 / +230
51
PWY PUR 2395
–30 / +90–20 / +195
52
PWB PUR 2395
–30 / +90–20 / +195
52
Permissible operating conditions
Please note that the values stated should be considered as guidelines only and not
as absolute values for practical applications.
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 53/60
53
Wiper seals, selection matrixPlease select the most important factor when choosing seal design.
Then study further factors, installation instructions and dimension tables in the
technical catalogue “Hydraulic seals”.
The number 5 in the matrix represents the most appropriate design while the
number 3 represents the least appropriate.
Type/series
Material
PA
PUR
PAK
PUR
PAD
PUR
GA
N
SCB
N
PWY
PUR
PWB
PUR
PO2
PTFE
PO
PTFE
High temperature, up to +110 °C (+230 °F) 4 4 4 4 4 4 4 5 5
Low temperature, down to –30 °C (–20 °F) 5 5 5 4 4 5 5 4 4
Friction 4 4 3 4 4 4 4 5 5
Surface insensitivity 5 5 5 4 4 5 5 3 3
Tolerance insensitivity 4 4 4 4 4 4 4 3 3Service life 5 5 5 3 3 4 4 3 3
Ease of installation 4 4 4 4 4 5 5 3 3
Fixiation in the housing 5 5 5 4 5 4 4 4 4
Wiping ability 5 4 5 3 4 4 4 4 4
Static sealing in the housing 5 5 5 5 5 5 4 5 5
Preferred in new designs X X X X X X X
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 54/60
Hydraulic seals
GuidesPlastic guide rings and guide strips guide the piston in the cylinder bore
and the rod in the cylinder head. They also accommodate side loads and
prevent metal-to-metal contact between these axially mobile parts.
SKF recommends the materials phenolic/fabric, acetal resin or PTFE for
guides, depending on the application.
Installation example for rods
Guide typesfor rod
Guide typesfor piston
Phenolic/fabric RGR-PF PGR-PF
Acetal resin RGR-A PGR-A
PTFE SB, SB/C SB, SB/C
Application field Phenolic/fabric Acetal resin PTFE
Mobile hydraulics x
Agricultural hydraulics x
Industrial hydraulics x x x
Process hydraulics x
Water hydraulics x
Food industry hydraulics x
54
Installation example for pistons
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 55/60
Static sealsThe O-ring, one of the most common sealing devices, is used in a variety of differ-
ent applications. The design is unique with its ingenious simplicity. The O-ring seals
through its deformation between the surfaces which it is supposed to seal. The work-
ing pressure at which the O-ring can be used is dependent on, among other things,
the installation method, fitting clearance, the O-ring material, sealed medium and
temperature. O-rings of a hard material generally provide an inferior sealing ability
at low pressures due to significant permanent deformation.
O-rings are often used as static sealing elements in hydraulic systems. However,
they tend to extrude into the clearance already at low pressures and are thereby
destroyed. An appropriate solution is to combine the O-ring with one or two
back-up ring(s).
55
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 56/60
56
O-ringsSKF normally stocks standard O-rings made of nitrile rubber 70° IRH. When neces-
sary, O-rings with the alternative hardness 90° can be manufactured upon request.
It is, however, better to choose 70° IRH and combine the O-ring with a back-up ring
when enough space is available.
For applications with temperatures over +100 °C (+210 °F), O-rings made of rubber
or silicone rubber are appropriate, depending on the medium.
In the catalogue, “Hydraulic seals”, you will find a wide range of O-ring sizes and
fundamental technical information. Detailed information about O-ring sizes and toler-
ances, installation instructions and, in some cases, material properties are found in
common national and international standards, e.g. SMS 1586 and ISO 3601.
Type ECOR is an O-ring consisting of a seamless and uniform PTFE encapsulation
that completely encloses the core material of either silicone or fluoro rubber to protect
it from media and air.
The function is the same as that of a normal O-ring that is compressed in the groove
and is working statically. Type ECOR is not appropriate for continuous dynamic opera-
tion due to its thin and soft encapsulation.
Advantages of ECOR:
Chemically resistant to aggressive media as a result of the PTFE encapsulation
Wide temperature range, –60 to +205 °C (–80 to +400 °F),
material type PFA +260 °C (+500 °F) Anti-adhesive, no stick-slip effects
Sterilizable, FDA approved
Low steam permeability and low water absorption
Low compression set solution
ECOR
OR
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 57/60
57
STR
Back-up ringsBack-up rings are intended to be used in conjunction with O-rings when the fitting
clearance between the surfaces sealed by the O-ring is large enough to allow the
O-ring to extrude at certain working pressures. In installations with normal and
standardized dimensions and tolerances, the O-ring normally must be complemented
with back-up ring(s) if the working pressure exceeds 10 MPa (1 450 psi), depending
on the temperature.
In applications where the O-ring is exposed to pressure from one side only, the back-
up ring is installed on the zero pressure side. For an O-ring exposed to pressure from
both sides, a back-up ring is installed on either side.
SKF back-up rings are stocked with a basic design and are made of either poly-urethane or of a polyester elastomer, for use together with O-rings according to
Swedish or British-American Standards, respectively. This enables the use of back-up
rings in most applications with normal pressure media and temperatures.
In applications with high temperatures or aggressive media, back-up rings of a PTFE
material are suitable, either unfilled or with an appropriate filler. SKF keeps a large
number of sizes of back-up rings of unfilled PTFE in stock. These are machine finished
and can therefore be delivered on short notice.
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 58/60
58
CRS1 Radial shaft seal 9
CRSA1 Radial shaft seal 9
CRSH1 Radial shaft seal 9
CRSHA1 Radial shaft seal 9
CRW1 Radial shaft seal 10
CRW5 Radial shaft seal 10
CRWA1 Radial shaft seal 10
CRWA5 Radial shaft seal 10
CRWH1 Radial shaft seal 10
CRWHA1 Radial shaft seal 10
CT1 Axial shaft seal 29
CT4 Axial shaft seal 29
CUT Hydraulic seal 34
ECOR Static seal 56
G Hydraulic seal 36, 45
GA Hydraulic seal 51
GC Hydraulic seal 36, 45
GG Hydraulic seal 36, 45
GH Hydraulic seal 36
GHTL Hydraulic seal 34
GH-XX8 Hydraulic seal 36
GL Hydraulic seal 36, 45
GLC Hydraulic seal 36, 45
GLG Hydraulic seal 36, 45
GN Hydraulic seal 36, 45
GR Hydraulic seal 36, 45
GS Hydraulic seal 36, 45
GS-XX8 Hydraulic seal 45
HDDF Axial shaft seal 30
HDL Radial shaft seal 13
HDLA Radial shaft seal 13
HDS1 Radial shaft seal 14
HDS2 Radial shaft seal 14
HDS3 Radial shaft seal 14
HDS4 Radial shaft seal 18
HDS6 Radial shaft seal 18
HDS7 Radial shaft seal 13
HDSA1 Radial shaft seal 15
HDSA2 Radial shaft seal 15
HDSB1 Radial shaft seal 15
HDSB2 Radial shaft seal 15
HDSC1 Radial shaft seal 15
HDSC2 Radial shaft seal 15
HDSD1 Radial shaft seal 16
HDSD2 Radial shaft seal 16
HDSE1 Radial shaft seal 16
HDSE2 Radial shaft seal 16
HMS4 Radial shaft seal 9
HMS5 Radial shaft seal 8
HMSA7 Radial shaft seal 9
HMSA10 Radial shaft seal 8
HS4 Radial shaft seal 19
HS5 Radial shaft seal 19
HS6 Radial shaft seal 19
HS7 Radial shaft seal 19
HS8 Radial shaft seal 19
HSF1 Radial shaft seal 17
HSF2 Radial shaft seal 17
HSF3 Radial shaft seal 17
HSF4 Radial shaft seal 17
HSF5 Radial shaft seal 17
HSF6 Radial shaft seal 17
HSF7 Radial shaft seal 17
HSF8 Radial shaft seal 17
HSF9 Radial shaft seal 17
LDSLV3 Wear sleeve 25
Product indexType/series Description Page Type/series Description Page
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 59/60
59
LDSLV4 Wear sleeve 25
MD-R Hydraulic seal 35
MUD1 Radial shaft seal 23
MUD2 Radial shaft seal 23
MUD3 Radial shaft seal 23
MUD4 Radial shaft seal 23
MUD5 Radial shaft seal 23
MUD6 Radial shaft seal 23
MUD7 Radial shaft seal 23
MVR1 Axial shaft seal 29
MVR2 Axial shaft seal 29
OR Static seal 56
PA Hydraulic seal 50
PAD Hydraulic seal 50
PAK Hydraulic seal 50
PEN Hydraulic seal 35
PGR Hydraulic seal 54
PO Hydraulic seal 51
PO2 Hydraulic seal 51
PWB Hydraulic seal 52
PWY Hydraulic seal 52
RD10 Radial shaft seal 11
RD11 Radial shaft seal 11
RD30 Radial shaft seal 11
RD60 Radial shaft seal 11
RD70 Radial shaft seal 11
RD71 Radial shaft seal 11
RDD13 Radial shaft seal 11
RDD14 Radial shaft seal 11
RDD15 Radial shaft seal 11
RGR Hydraulic seal 54
SA Hydraulic seal 38
SB Hydraulic seal 54
Type/series Description Page
SC Hydraulic seal 54
SBF Radial shaft seal 18
SCB Hydraulic seal 51
SKF SCOTSEAL
CLASSIC
Radial shaft seal 24
SKF SCOTSEALLONGLIFE
Radial shaft seal 24
SKF SCOTSEAL
PLUS XL
Radial shaft seal 24
SG Hydraulic seal 42
SIL Hydraulic seal 42
SKY Hydraulic seal 43
SKF SPEEDI-
SLEEVE
Wear sleeve 25
STR Static seal 57
STR-D/A Hydraulic seal 43
SUA Hydraulic seal 38, 44
SUD Hydraulic seal 38, 44
SUS Hydraulic seal 38, 44
TIL Hydraulic seal 42
UN Hydraulic seal 43
URG Hydraulic seal 35
VR1 Axial shaft seal 28
VR2 Axial shaft seal 28
VR3 Axial shaft seal 28
VR4 Axial shaft seal 28
VR5 Axial shaft seal 28
VR6 Axial shaft seal 28
Type/series Description Page
8/13/2019 SKF Sealing
http://slidepdf.com/reader/full/skf-sealing 60/60
® SKF, SPEEDI-SLEEVE, SCOTSEAL and WAVE are
registered trademarks of the SKF Group.
™ DURATEMP is a trademark of the SKF Group.
© SKF Group 2008
The contents of this catalogue are the copyright of the
publisher and may not be reproduced (even extracts)
unless permission is granted. Every care has been taken
to ensure the accuracy of the information contained in this
catalogue but no liability can be accepted for any loss or
damage whether direct, indirect or consequential arisingout of the use of the information contained herein.
The data in this publication may differ from that shown in
earlier publications because of redesign, technological devel-
opments or revised methods of calculation. SKF reserves
the right to make continuing improvements to SKF products